Desire's Catalyst
by Penguita38
Summary: Yuuki buys a love potion with the intention of swooning her two favorite vampires, but what she didn't think to do was read the side effects. K/Z. Birthday gift for KanameZero4Eva. Happy belated birthday, KZ4E!


Happy (very belated) birthday, KZ4E! KZ4E (KanameZero4Eva), this if for you. ;)

I wrote this as a birthday gift for KanameZero4Eva, because (as I'm sure other writers agree) is a wonderful reviewer, and has since become a wonderful friend. She is amazing, always faithful, and hilariously witty. I'm sorry it isn't insanely long or bursting the seams with my normal amount of detail, but I think it's enough to get your temperature rising, KZ4E. :)

Seeing as it's nearly 5 a.m. – any errors are mine. As always.

**Warnings:** It contains situations between two males (KanamexZero), so if you can't stand two guys getting their kink on, then I suggest you click the back button. Now. :D

Disclaimer: I don't own Vampire Knight. Not now. Not ever.

**Desire's Catalyst**

Zero lifted a steady brow in response to the small pink bottle Yuuki waved in front of him.

"Yuuki, you're an idiot," Zero mumbled. "A complete moron, with idiotic bells and whistles attached to compliment the moronic ensemble."

"Zero, don't be so mean," she said, her lips full and puffy as she attempted to pout her way to his heart. "Read the label again, okay? It says it'll work!"

"And magicians say it's actually magic," he said with a snort.

She pushed the bottle into his palm, and then forced his fingers closed. "Look at it," she demanded.

He sighed and focused on the small black print on the front of the pink label.

_Bring out his deepest desires in just thirty minutes! _

Yuuki had dragged him to town nearly two hours ago, her little legs moving from store to store, and his arms filling with more and more bags. They were supposed to find a dress for the dance next weekend. They were both required to attend and represent the school as the Guardians. And after two hours, she had found the perfect lavender dress, topped off with all the fluffy tulle and pink sequins a girl could want. He was glad, too. He was afraid his eyes would've fallen out if he was forced to watch Yuuki twirl around in another dress that looked exactly the same as the last dress she tried on, but no, that one was a different color and waist shape, and the folds in the fabric weren't crinkled on the other one…

But now he was here. She had pulled him into a small store at the end of the walkway. The wooden sign had spelled it all out for him clearly: "Madam Mysteries Moment Makers." Oh, he forgot to add there was a tiny marking beneath it, etched in black that said, "AKA: MMMM."

And that reminded him of what he was currently doing, which was glaring at a tiny bottle with vehement. Yuuki seriously believed that this stupid "love potion" would bring her _Kaname-sama_ to her feet, asking for her to marry him? She was an idiot.

"Like I said, Yuuki, stupid. This is just some strawberry laced water. It smells like those plastic dolls you have in your room." He shoved the bottle back in hand. "Can we leave now?"

"I'm going to try this on you then, Zero," she said with a wink, and then added, "and Kaname. I'll have you both fighting over me before the nights over."

"Whatever," he grumbled. "Just buy it already so I can get the hell out of here."

And she did, skipping all the way home with her new love potion in hand.

…

"Isn't it pretty?" Yuuki spun around in the living area, her hands flared out as she twisted until the bottom of the dress fanned out.

"Oh, my daughter is so beautiful," the Chairman cooed. He beamed a smile from ear to ear, snapping several pictures of his "daughter" as she pranced around.

"Did anyone else forget that dinner is in fifteen minutes?" Zero asked, and then sighed and retreated back to the kitchen. He added, "Of course not," under his breath.

He made sure the dinner was prepared and then set the table with four plates, chopsticks and cups. He placed the pots on the center of the table and then sat down in the chair furthest from the kitchen door. Yuuki came in minutes later, wearing a pair of blue Capri's and a plain pink T. She whistled as she poured the lemonade into the glasses. She swayed her hips dramatically, knocking a set of chopsticks to the ground.

"Oops," she sung. "Do you mind grabbing those, Zero?"

He sighed, leaned over and picked up the sticks. When he looked up, Yuuki was wide-eyed and wore an overly innocent expression, rolling her eyes around as she shrugged and disappeared through the kitchen door.

Strange girl, he thought.

A knock at the door caused the Chairman to flit past the dining room. He heard Kaname saying hello before the front door slammed shut.

His night of hell was about to start in three, two, one…

"Kiryu," Kaname said, "the food smells delicious."

He grunted a response and nodded.

"Oh, Kaname-senpai!" Yuuki squealed. "I'm so happy you came."

"I'd never miss a dinner invitation from you, Yuuki."

He was going to be sick very shortly.

Before he could glare back at Kaname for the fourth time that night, everyone was sitting down and laughing over a plate full of food.

"This lemonade is very…unique, Kiryu," Kaname said. "You wouldn't have poisoned it, would you?" The pureblood's expression clearly said he was serious, even though he chuckled as he spoke.

"I'd be a little more creative than poison, Kuran," he replied with a grin. "I'd just shoot you."

Kaname smiled. "Of course you would." Then added lowly, "If you could."

"Whatever, Kuran. Yuuki made the lemonade, anyway, so bug her about it."

But there _was_ a strange aftertaste to the juice now that Kaname had mentioned it. It tasted like someone had put hand soap in it, but there was a sweet undertone to it that he couldn't pinpoint. But considering it was the only drink in the house—literally—he would have to finish it off.

Another fifteen minutes and three gulps later, the drink couldn't quench the undeniable thirst building in his throat. He loosened his tie and unbuttoned his top button, airing the area out. He was so hot. He coughed, reaching for his glass to take another sip.

"Are you okay, Kiryu-kun?" the Chairman asked.

Was he sweating? His forehead felt wet, but when he rubbed the back of his hand across it, it came back completely dry. He snapped his head up and stared at his adopted father, his eyes zooming in on the pale skin that curved from the Chairman's jaw to his shoulder. The veins pulsed visibly, like blue cords strumming against creamy flesh. He licked his lips, gulping down forcefully, imagining how warm the blood would be when it slid down his throat…

"Oh, god," he yelled, standing up and flipping his chair over.

"Zero, are you alright?" Cross asked again.

"I…umm…" The blood drummed in his ears, but it wasn't just his own. He could hear every single heartbeat in the room, their pulses like a drug calling to him. "I've…just…"

He turned. He had to get out of the room. Now. He steadied his body on the table, inadvertently knocking over Kaname's plate right onto the pureblood's lap. Red sauce splattered up and coated the vampire's white jacket with scarlet speckles. And it looked like blood—sweet, addicting, thick blood.

He really needed to leave.

"Sorry," he mumbled. "Gonna lie down. Not feeling well," he said in a rush.

He left before any of them could say anything. He darted to the bathroom, closed the door, and then slid down the wooden frame until he hit the tile. His chest heaved as he gripped the front of his shirt. Somehow, he managed to crawl across the floor and to the sink. He ran the water until it turn ice cold and then dipped his entire head under the faucet. His veins were on fire. His whole body shook with a craving he had never felt before. He wanted blood, but then more, and he could feel the fierce undercurrent as something unknown swarmed his senses.

A knock at the door pulled him briefly from his bodily hell.

"Go away," he yelled at the pureblood. He could sense the vampire's aura, and strangely he wanted to open the door, let Kaname in, and then drain him until nothing was left but an empty shell of a pureblood. "Seriously, Kuran, I'm warning you to get the hell away from the door."

"I need to use the restroom, Kiryu. Someone spilled red sauce all over my clothes." The added sarcasm wasn't helping the situation.

"There is a guest bathroom," he said. "Use it."

There was a soft click as the door unlocked. He stared wide-eyed as his barricade was breached by the pureblood's power. He started to scoot away from the door, his back hitting the window.

Kaname's body slinked through the opening, the door closing quietly. The clack of the metal lock was oddly louder, as the pureblood snapped it back into place. Kaname unknotted his tie, sliding the fabric free. It fell to the floor silently. All he could look at, though, was the visible skin behind Kaname's black shirt collar. The call for the pure blood was stronger than any other blood.

"You want it?" Kaname asked, a deep roughness to his tone that didn't go ignored.

His feet moved on his own, and before he could even contemplate what the hell he was doing, he had the pureblood pushed up against the door. The warm skin satisfied the fire from his body, even if there was a layer of clothing between them.

"More than anything," he whispered in reply, and then started at the buttons on Kaname's shirt, peeling the shirt open one by one.

His lips met Kaname's flesh with satisfaction, a deep growl that rumbled in his chest as his tongue darted out and lapped a trail down the curve of skin beneath him. His fangs were seriously aroused, and the pain throbbed in his gums and throat. He needed to be sated, and it was a desire he had no control over.

He pierced the skin swiftly, humming in delight when a rush of warm blood poured into his mouth. He knew he was rough with his bite, but he couldn't stop his fangs from sinking further and further into the wanting flesh. He drank in large gulps, opening his mouth wide to allow more blood to flow over his lips. He felt the liquid spill over and down his chin. He was messy, but the need masked any sense of etiquette.

Kaname's hands were on his shirt, tearing at the buttons until they snapped. He vaguely heard the plastic rounds hit the tile, like several beads that popped against a hard surface. His mind wandered off, and then clicked into nothing but the urgency of desire he needed to fulfill. He wanted it all. But there was still a hallow pit in his lower stomach that filled with pressure, a need for something more than just blood.

He was lifted onto the vanity counter, his back smashing into the mirror. It shattered as he body was slammed into the glass. The sound was there, but distant as the pieces spilled all over the ceramic countertop. Kaname worked the shirt off Zero. He kept his teeth imbedded in Kaname's neck, drinking more than he could, and it still didn't satisfy the ache inside of him.

Pain flared down his wrist, a sharp streak of agony that quickly faded as soon Kaname's mouth was on the wound.

He let go of Kaname with a gasp, his head hitting the wall. His gaze caught sight of the bloody piece of glass the pureblood must have used to slice open his wrist. His breath came in quick pants at the sound of Kaname sucking on his wrist. It oddly was stimulating. He wanted the pureblood to take more of him. Take it all. It didn't matter. He just wanted…wanted…Kaname to take all of him. And he needed more in return.

A knock on the door jolted him. He sneered at the intrusion. The pureblood ignored the noise, and kept both of his hands wrapped around Zero's forearm as he pushed more of Zero's blood to him.

"Zero," Yuuki asked. Her voice was muffled from the door. "Are you okay? I heard a noise."

"I'm fine," he said, trying to regain control of his voice. "I just… Ah, _God_," he hissed as Kaname's fangs drove into his skin finally.

"Zero?" she asked again, concerned.

"I'm… I'm fine. Go away," he whispered, unsure if she could actually hear him. And quite honestly didn't care. The fire inside of his body was spreading quickly through his veins. "Shower. I'm gonna…" Kaname bit down harder. "_Shit_. Shower."

As if on cue, the shower turned on without anyone actually moving the handle. Kaname's powers were handy at times like this.

"Oh, okay…" she said. "I hope you feel better, Zero. Let me know if you need anything."

Oh, he did need something, but he was sure she couldn't douse the raging heat inside. The pureblood seemed to have that part under control. The more Kaname touched him, the more he needed, and the more unbearable the pressure became. Only the pureblood could quiet it down. He didn't know how he knew, but he did. The connection was intense on both sides, and he could feel Kaname's need in his blood as he drank. It was the same as his.

Kaname let go of his wrist, his fangs sliding free slowly. There was blood everywhere. It stained the white counter, Kaname's jacket and skin, and Zero's arm.

Their lips were like magnets, drawn to the blood of one another. They clashed, fangs and tongues both hitting as he coiled his fingers in Kaname's hair and pulled the pureblood closer. The messy pain was like a catalyst that sparked the fire deep within them.

His other hand worked on shrugging the pureblood free of his jacket and shirt. He wrapped his legs around Kaname's hips and drew the pureblood to him. He felt Kaname's arousal hit his own. And with sudden clarity he understood what the other need was. He needed to be filled in both blood and flesh.

He wanted it so badly his chest ached.

Kaname was the one who broke the kiss, his bloody lips falling to Zero's neck, sucking and nipping the skin with a fiery force that reddened. He moved down, continuing his brutal kisses in a path that left Zero's chest both bruised and bloody. Then there were fingers at his pants, nimble and quick as they worked the button free and yanked them down his legs. His boxers were next, and he didn't feel embarrassed or ashamed to be completely naked, spread out on the sink counter while the pureblood's eyes raked over his nude form.

And slowly, as if to torture, Kaname removed his own pants, sliding the fabric down his thighs with careful ease. He watched, mesmerized by the sight, and by the hard length that he knew was the key to quench the desire burning in his blood. He licked his lips in anticipation.

Kaname was back on him, lower this time, his mouth gliding over his stomach. He stopped and paid special attention to Zero's hips, covering it with his mouth and running his tongue along the small dip of skin. It caused his body to tingle, a shiver that forced his legs up until the heels of his feet settled atop the pureblood's back.

A heat—that nearly exploded in his stomach—shot up his muscles, as Kaname engulfed his length. The sounds were everywhere in his ears. The harsh pants that came from him, the glass scraping against one another when he moved his hands, and the wet suction from the pureblood's mouth around him.

The pleasure was like a warm fountain rushing over him, but he needed more.

His hips started to move up on their own. He wanted to be deeper inside Kaname, and the pureblood didn't seem to mind, taking him to his fullest.

His bloody hand reached out to the brown hair between his legs, his fingers combing through the strands as if to coax the pureblood to keep going and never stop.

But Kaname did stop, and with one long lick against his member, the pureblood rose, pushing Zero's body until the hunter's back was against the wall. Kaname grabbed Zero's hips, dragging them forward, until the latter end of the hunter hung off the counter.

The pureblood's warm fingers were at his lips, ghosting over the soft skin and begging for entrance. He complied, more than willingly. Two fingers caressed his tongue, and he did his part, sucking them in and wrapping his mouth fully around them.

Lust glinted in the pureblood's gaze when he popped the fingers free. They were wet, dripping, and his eyes watched in earnest craving as they were lowered between his legs. Slowly, too slowly, one finger was pushed inside. He winced at the intrusion, but then relaxed, his need to go further overcoming the discomfort.

"_Shhh_…" the pureblood cooed.

He bit his lip in response. A second finger followed, stretching him even further. He sat up abruptly, coiling his arms around the pureblood's neck. He breathed in the scent of Kaname, finding it strangely calming. The blood from their messy feeding earlier was smeared across the alabaster skin, and he found his mouth drawn to the metallic drug, licking Kaname's neck with fervor.

The pureblood shivered in response, and Zero knew he found a sensitive area. He pulled the skin into his mouth, sucking until he knew the area was raw and bruised. His fangs brushed along the pureblood's neck, bringing forth beads of new blood that he quickly lapped up, only to do it all over again. He did that for too many long, agonizing minutes, until Kaname slid his fingers out, and brought Zero's legs to his waist. Instinct kicked in, and he wrapped his legs around Kaname and locked his ankles together.

Pressure filled him, a thick force that entered him. He hissed, unable to hold back the string of curse words that flew from his mouth. It hurt. A lot.

"Shit," he cursed.

He had forgotten about the running shower until a warm fog wrapped around his body. The glass pieces were smeared white from the condensation of hot air. He let go of Kaname and moved to grip the edge of the counter. His bloody wrist started to sting as all the pain on his body was magnified. The cloud of pleasure that coated the pain was shattered as soon as the pureblood pushed in further.

It felt like forever before the pain ebbed and was replaced by pleasure. Kaname's head brushed against something inside of him that caused his body to shake.

"Ah," he whispered. "That. Again. Do it." He knew his words were broken, but he couldn't muster up enough brainpower to string them together and make them coherent.

"Gladly," the pureblood responded, his breath on the side of Zero's neck. He could feel the heat from Kaname's words in more ways than one.

His desire was still hungry for more, but he felt the need coming down as the pureblood moved in him. Each thrust brought him closer and closer to his finished goal.

His breath came in heavy pants. The sweat that formed on his forehead was lost in the humidity of the room. They were sticky, wet, and sliding perfectly against one another. Zero ran a free hand down Kaname's shoulder, bringing more blood to surface. He smeared his finger across the pureblood's open mouth, staining the pink lips red.

"Zero." Yuuki was back. "Are you sure you're okay? You've been in there a long time. I'm getting worried."

He opened his mouth to say something, but just then Kaname thrust in hard, a wicked smile adorning the pureblood's face.

He tried again, shamed at how ragged and hoarse his voice sounded. "Fine, Yuuki. Swear. G-g-o—_oh_!" He stuttered the last words when Kaname pulled out and then pushed back in, going in deeper than he had before.

The pureblood snickered in delight.

"Bastard." He glared at Kaname.

"What?" Yuuki asked. "Oh, Zero, have you seen Kaname-senpai? He disappeared shortly after you spilled food on him."

Kaname was at his ear, his hot breath distracting him from the problem on the other side of the door.

"Yeah, Kiryu," Kaname whispered slowly into his ear. "Have you seen me?"

The pureblood moved quickly, catching his lips in a searing kiss. He was lost in the moment, opening his mouth wide, allowing Kaname's tongue to enter. It made him dizzy, disconnected, and he had forgotten all about his best friend. He was too entranced by the pureblood to care about anything else.

"Zero? Are you sure you're okay?" Yuuki reached his mind.

"Ah," he breathed out loudly, craning his head upward and away from the delicious mouth he wanted. "I'm fine, Yuuki. Promise." He wheezed. "Kuran probably—."

"You're fine?" Kaname said with a smirk. "How about now?"

Kaname drove his fangs deep into his neck. A wave of pure heat crashed into his body.

"—went hom—_mme_—_Shit_!" he said, a little too loudly. The combination of Kaname's member moving inside of him and the fangs in his skin caused him to lose it.

"You're acting strange, Zero. Let me know if you need anything," Yuuki said. He could see the frown on her face in his mind, and how her shoulders dropped as she sulked away. He would mend that relationship later. But now…

"You're twisted," Zero hissed.

"I know," Kaname murmured, pulling his fangs free.

The pureblood didn't wait for a reply. Instead he pushed into Zero, hard, over and over until the hunter was a mess of gasps and swear words. It was moments after that that Zero climaxed. He lost himself in the pure ecstasy that rippled from his core and down his legs. Kaname still had a few more thrusts before he came, and when he did, his arms wobbled and his legs trembled from the pleasure that hit him.

The haze was lifting, and when he opened his eyes for what felt like the first time, he saw what their pleasure had caused. The bathroom was in disarray. The mirror was broken, the shards lying all over the sink and floor, and there was blood everywhere. It was smeared on the sink, the wall, and their skins… Zero's shirt was a scarlet mess on the rug, and the pureblood's was not any better, his jacket and shirt in a heap near his. The only things that came out unscathed were their pants.

Zero's breathing was leveling out finally. He inhaled deeply, and was thankful they weren't in a house of vampires. Their scent was everywhere. It clung to the air, the walls, and most importantly, them.

Kaname pulled out slowly, and Zero arched his back as his already sensitive area was assaulted by the sensation.

"What the hell…?" Zero trailed off, his gaze taking in the mess.

"I believe we had sex, Kiryu."

"I get _that_, idiot. The mess…"

"Was desire that climbed out of control," Kaname said.

"Move," Zero instructed, and pushed the pureblood so he could hop off the glass-ridden countertop.

They both sat there for a moment, naked, and utterly shocked at all the damage they had truly caused. The wall was broken from where Zero had slammed into it, a part of the drywall hanging and exposing a set of rusty pipes from the inner structure. And that was just one thing added to the already long list of destruction.

As soon as they had their pants on, a soft knock came to the door. Zero shut off the shower, thankful that all the hot water had faded out, the cold replacing it, dissipating the thick cloud of steam in the small bathroom.

"Yes, Yuuki?" Zero asked, knowing already that she was at the door again.

"Zero, I, um… I'm so sorry," she whispered. "I should have read the warning label, you know. But I was so caught up in the idea of you two, with me, you know."

His brows crinkled. "What are you talking about?"

"The love potion. I think I made you and Kaname-senpai sick."

"Why…?" He was almost afraid to ask.

"The label on the back says: 'Do not use on werewolves, fairies, and vampires. Serious side effects include: Desire to eat people, drink blood, and uncontrollable urges seen mainly in supernatural creatures. In less serious cases, only vomiting occurs. Do not take if you are pregnant, or think you may be pregnant."

"Yuuki, you didn't…did you?" he asked. He knew his eyes were already wide with fear.

"Yeah. In the lemonade. I'm sorry, Zero. I think I made you and Kaname sick," she said, sincerely apologetic.

Zero turned around to glare at the pureblood, who was quietly chuckling behind him. Kaname was perched up in the open window. He grinned at Zero.

"We should do that again sometime, Kiryu." And then he was gone, leaving Zero with the mess and explanation as to why the bathroom needed a complete makeover.

"Shit," he muttered.

…

Aw, I always write rather dirty lemons when they are stand-alone. So, KZ4E, this is for you, my friend. Thank you for being there for me when I've needed, and for the laughs. I truly hope you had a wonderful birthday. And, because it's me, hopefully you can forgive me for the tardiness of yet another update. :D LOL! I'm never on time. Ever.

I wrote this to Linkin Park's new single: "The Catalyst"

Hope you all enjoyed. Let me know. :D


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